1. Field of the Invention
The present invention relates to a sheet processing apparatus and an image forming system.
2. Description of Related Art
In order to achieve miniaturization and better operability of a saddle stitching bookbinder, some known bookbinders have been configured as follows. A trimming section for a fore edge is placed at the bottom of the bookbinder while an ejecting section is placed at the top. The bookbinder conveys a saddle-stitched booklet in the up and down direction while the first holder holds the booklet in a vertical state where the crease of the booklet is at the top and the fore edge is at the bottom.
When the bookbinder with such configuration trims a fore edge, a part around the crease of the saddle-stitched booklet must be held so that the booklet is sufficiently inserted into the trimming section. Also, when the saddle-stitched booklet is passed to the ejecting section, a part around the fore edge must be held so that the booklet is sufficiently inserted into the ejecting section. Thus a part of the saddle-stitched booklet by which the booklet is held must be changed.
One possible method for changing the part by which the first holder holds the saddle-stitched booklet is, for example, to provide the second holder which holds the booklet from below. While this second holder temporarily holds the booklet, the first holder changes the part by which the holder holds the booklet.
As for the second holder which holds the booklet from below, Japanese Patent Application Laid Open Publication No. 2010-1109 discloses a tray which includes a sheet receiving unit at its bottom and which is set in an inclined state although it is approximately vertical. This tray includes a pressing member that presses stacked sheets.
The tray described in the above publication holds a bundle of sheets while the sheet receiving unit contacts a fore edge of the bundle of sheets (saddle-stitched booklet). Such configuration may damage the fore edge of the bundle of sheets.
Further, the pressing member of the tray described in the above publication presses a surface of the sheets with its flat surface. Therefore, when sheets are not hard enough or the like, the sheets may fall flat.